Rapid start and stop clutch mechanism for phonographs



May 18, 1948. 11H. NAKKEN 2,441,836

RAPID swam AND smop CLUTCH MEcHANrsM Fon PHoNoGmPHs Filed June"19,'1944 s sheets-sheet 1.

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RAPID START AND STOP CLUTCH MECHANISM'FIO-R PHONOGRAPHS Filed June 19, 1944 s sheets-sheet 2 ATTORNEY 1411939191948. "T. HjNAKKE'N 2,441,836

RAPID START AND STOP CLUTCH MECHANISM FOR PHONOG'APHS F'nd June 19, 1944 n a she/45199669 s ATTMEY Patented May\l`8, 1948 UNITED STATES PATENTEoFFlca to The Soundsciiber Corporation, New Haven, Conn., a corporation o! Connecticut AAppliance June 19, 1944, serial Nu. 540,929

2 Claims. (Cl. 274-1) This invention relates to phonographs of the sound reproducing apparatuses.

One object of this invention is to provide an improved start and stop mechanism for a phonograph turntable to permit the latter to be started and stopped with the minimum amount of lost motion, and without slowing-down or speedingup periods which might give rise to changes in pitch.

A further object is to provide a start and stop mechanism of the above nature in which the clutch is mounted to connect the motor drive shaft with the turntable spindle, and made quite compact so as to reduce the height of the machine.

A further object is to provide a device of the above nature which will be simple in construction, inexpensive to manufacture, easy to install and manipulate, ornamental in appearance, and

y Fig. 1 is a side view of a clutch mechanism ernbodying the present invention.

Fig. 2 is a transverse sectional view of the same, taken along the line 22 of Fig. i, looking downwardly in the direction of the arrows.

Fig. 3 is a sectional view of the same, on a larger scale, taken along the line 3 3 of Fig. 2.

Fig. 4 is a diagram showing the electrical circuits of the improved clutch mechanism.

This invention is an improvement over the inventlon disclosed in the United States Patent No. 2,240,320, of April 29, 1941, for Quick start and stop mechanism for phonograph turntables, and U. S. Patent No. 2,278,680, of April 7, 1942, for "Quick start and stop drive mechanism for phonograxph turntables, both of which patents were vgranted to Lincoln Thompson.

The present invention is of particular importance 4for use in a transcriber afa disk record type of dictating machine because it enables the record to be started and stopped with extreme rapidity and without stopping the motor, which runs continuously. It may also be used during the recording of dictation -for rapidly starting and stopping the record and for simultaneously stopping the feed f the recording' arm across the record. l

Referring now to the drawings. wherein like reference numerals designate like parts throughout the several views, the numeral I0 indicates the chassis of a dictating machine which is driven by a motor 46 (seefFig. 4) having a vertical shaft II which in turn drives a turntable I2 by means of'a flexible clutch connection between the shaft II and a turntable spindle I3-the latter being mounted in a bearing I 3a secured to the chassis I0 by a half ilange |31?.

The motor 46 is mounted upon a plate I4 supported from the chassis I0 by means of four pillars I5, Iii, Il, I 8, said pillars being surrounded at their lower ends by rubber grommets Iaa. Provision is also made of an eleotromagnet-supporting plate I 9 made of iron which is suspended from the chassis I0 by means of a plurality of vibration reducing lters 2 0, each of which includes a spring and a snubber member.

Depending from the plate I4 are a pair of elecvtromagnets which when energized attract an upper clutch plaie 24, thus disengaging the clutch and thereby stopping the turntable driving spindle I3 substantially instantly, as will be hereinafter more fully described.

Provision is made of a lower circular clutch plate 2l having an upper leather clutch surface 22, andaI depending iiywheel rim section 23 which serves to smooth out gear rumble due to any possible inaccuracies in the gear meshing. The plate 2i is secured as by a set screw 23a to the motor shaft it.

The upper circular movable iron clutch plate 2d has a lower clutch surface 25 of leather and an upper annular ring 26 of cork for engaging a. pair of ironcores 21 depending from the iron plate i9. The cork ring 25 on the upper clutch plate 24 serves to eliminate noise when said plate makes contact with the cores 2l of the electromagnets. The cores 21 are surrounded by a pair of electromagnetic coils 2B, each of which has terminals 29 and 30 connected to any suitable source of direct current, such as an A. C. rectier 45 (shown in Fig. 4).

The upper iron driven clutch plate 24 is flexibly mounted concentrically with the turntable spindle I3 and is adapted to be pressed into contact with the lower driving clutch plate 2| by means of an adjustable coiled spring 3| which presses downwardly upon said upper plate 24. The spring 3I is engaged at its upper end by a screw collar member 3io having a knurled ilange SIb, said collar member being adjustably mounted on a threaded bushing 3Ie secured to the spindle i3 as by a set screw 3 Id, as shown.

The upper clutch plate 24 is provided with a central aperture which is covered by a iiexible canvas membrane 33 secured to said upper clutch plate.24 by ineans of a plurality of outer rivets 34, said rivets having their upper heads seated upon an outer cover ring 35. The inner portion of the canvas coupling membrane 33 is secured to a central coupling stud 36, as by an inner cover ring 31 and inner rivets 38 and said stud 36 is screwed into a left hand threaded aperture in the bottom of the turntable spindle I3, thus providing for an extremely flexible universal coupling having vertical exibility with a minimum of rotational flexibility. This .fabric center coupling also serves as an effective filter for motor vibrations.

In order to stabilize and level the movable iron upper clutch plate 24 and complete the magnetic circuits through the iron plates I9 and 24, a pair of diametrically spaced additional iron studs 39, 39 are provided, which are located symmetrically between the pair oi.'A electromagnetic coils 28, 28.

The turntable I2 is rigidly secured to the spindle I3, as by a drive fit, and is embraced by a disk-supporting shell 40 having a depending exterior rim 4I, said shell 40 resting upon a cork vibration iilter ring 42 seated in an annular outer Irecess 42a. in said turntable I2.

In order to feed the recording head 49 slowly across the record 48, the spindle I3 is provided with a short worm gear section 41 which engages with a worm (not shown) mounted on a connecting rod (not shown) drivingly connected with the recording head arm 50. This construction is fully described in the prior U. S. Patent No. 2,133,596, granted October 18, 1938, to Lincoln Thompson, entitled Feed mechanism for disk recording machines.

Operation It will be understood that when out of use, the upper and lower clutch plates 24- and 2| will be in abutment, as shown in Figs. 1 and 3. When the motor switch 44 and the manually-operated clutch switch 43 are closed, the clutch plates 2| and A24 will remain in abutment until the tubes of the rectifier 45 have warmed up sufficiently to energize the coils 28 with the rectified D. C. from the rectier, which is supplied with power from line wires L1, and L2. The cores 21 of the eiectromagnets will then attract the upper clutch plate 24 and cause it to move away from the lower clutch plate 2|, thus stopping the turn-l table I2. The motor 46, clutch plate 2|, and

4 to stop the rotation of the turntable substantially instantly.

It will be understood, of course, that while dictating whenever the turntable I2 and its spindle I3 stop rotating, by disengaging the clutch plates 2| and 24, the recording arm feed' will also be stopped. thus avoiding waste of the recordlng space on the record.

It will be understood that during the upward and downward movements of the upper clutch plate, the shocks due to the engagements of said plate with the electromagnet cores 21 and the lower clutch plate 2|, respectively, will be cushioned by the filters 20. Any tendency for the recording and reproducing needles to leave their proper grooves will thereby be eliminated..

While there has been disclosed in thisgjspecication one form in which the invention may be embodied, it is to be understood that this form is shown for the purpose of illustration only, and that the invention is not to be limited to the specific disclosure, but may be modified and embodied in various other forms without departing from its spi.it. In short, the invention includes all the modifications and embodiments coming within the scope of the following claims.

Having thus fully described the invention, what is claimed as new and for which it is desired to secure Letters Patent is: A

1. In a clutch for rapidly starting and stopping a phonograph turntable having a spindle, an out-l wardly-extending disk secured to the lower end of said spindle, a continuously-rotated motordriven shaft in alignment with and longitudinally spaced from said spindle, a lower clutch plate secured to said shaft, an upper iron clutch plate having a central aperture concentric with said disk, a flexible membrane, means clamping portions of said membrane to said upper clutch plate shaft II will, of course, continue to run at full speed.

Whenever the electromagnetic coils 28 are thereafter deenergized by opening the normally closed clutch switch 43, the current will be shut off from the electromagnetic coils 28, and the and said disk, respectively, whereby said upper clutch plate isflexibly connected with said spindle, spring means for normally holding said iron clutch plate in engagement with said lower clutch plate, and manually-controlled electromagnetic means for attracting said iron clutch plate to move it away from said lower clutch plate against the action of said spring to stop the rotation of said turntable spindle.

2. A clutch as defined in claim 1, in which said electromagnetic means includes a plurality of electromagnets located above said iron clutch plate, and a manually-controlled switch for opening and closing the circuit through said electromagnets.

THEODORE H. NAKKEN.

REFERENCES CITED v The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 511,621 Johnston et al Dec. 26, 1893 1,288,270 Stuart Dec. 17, 1918 1,853,864 Kingston Apr. 12, 1932 2,240,320 Thompson Apr. 29, 1941 2,251,020 Murphy July 29, 1941 2,278,680 Thompson Apr. 7, 1942 

